This invention relates to a control apparatus for a hybrid vehicle for enabling driving of a vehicle, even if a high voltage line including a electric motor has failed.
Some motor vehicles are of a type commonly called a hybrid vehicle having an internal combustion engine and an electric motor disposed therein as the power sources of a propulsion system. The hybrid vehicle further includes an engine control means for controlling a running state of the engine and motor control means for controlling an operating state of the motor. The engine control means and the motor control means detect respective operating states of the engine and the electric motor when the vehicle is traveling, and then exchange such detected data regarding the running states. As a result, the respective operating states of the engine and the motor are controlled in association with one another. Such a control system attains a high level of required performance (such as fuel efficiency, lower values of detrimental components in exhaust gases, and power performance).
Such examples of a control apparatus for a hybrid vehicle are disclosed in published Japanese Application Laid-Open Nos. 7-115704, 8-98318, 9-56007 and 10-174201.
However, in a retarder apparatus disclosed in published Japanese Application Laid-Open No. 7-115704, a countermeasure when motor (12), and controller (34), and rising voltage chopper rectifying circuit (32) have broken down or failed, is not mentioned.
In a control method of a hybrid type electric vehicle disclosed in published Japanese Application Laid-Open No. 8-98318, a motor (18) for traveling only becomes in an usable state. Therefore, an engine is not a drive source for traveling, and drives an electric power generator. Accordingly, in such structure of a vehicle, when motor (18), battery for traveling (20) and EV-ECU (26) have broken down or failed, then the vehicle becomes unable to travel.
In a hybrid vehicle disclosed in published Japanese Application Laid-Open No. 9-56007, a low voltage line of 12V (24V) and a high voltage line of 36 to 228V are independent. However, a method for start-up of an engine and a countermeasure when a controlling power supply (low voltage) to inverter (30) and high voltage line have broken down, are not mentioned.
A power-supply unit for a supplementary apparatus of a hybrid electric vehicle disclosed in published Japanese Application Laid-Open No. 10-174201 is similar to that of above-mentioned Japanese Application Laid-Open No. 8-98318.
Incidentally, in a control unit of a traditional hybrid vehicle, the usual power supply of 12V is made from high voltage (150 to 300V) battery for motor by a DC/DC converter. Accordingly, a low voltage battery of 12V is possessed, but, an alternator that is an electric power generator is not equipped. Thus, because a high voltage battery is main, when the high voltage battery is down, a function of the vehicle will be stopped.
Further, in order to function properly without a high voltage battery going low, an expensive battery consisting of a nickel/hydrogen battery or a lithium ion battery is necessary. Then a complicated battery administrating function becomes necessary, and there is inconvenience and the system is disadvantageous in practical use.
In order to obviate or minimize the above inconvenience, the present invention provides a control apparatus for a hybrid vehicle mounted with an engine and an electric motor which is connected to an output shaft of the engine. The control apparatus includes an engine controller which controls a running state of the engine. A motor controller controls a driving state of the electric motor independently from control of the engine by the engine controller. A first battery and a second battery which has a higher voltage than the first battery are provided. An electric power generator driven by the engine is provided for charging the first battery. The second battery and the electric motor are connected through the motor controller. The first battery or the electric power generator is connected to the motor controller for maintaining a power supply for operation maintenance of the motor controller and is connected to the engine controller for maintaining a power supply for operation maintenance of the engine controller.
In addition, the present invention provides a control apparatus for a hybrid vehicle wherein the first battery or the electric power generator is connected to the engine controller for maintaining a power supply for operation maintenance of the engine controller. The second battery or the electric motor is connected to the motor controller through a DC/DC converter for maintaining a power supply for operation maintenance of the motor controller.
According to the present invention as previously described, in a control apparatus for a hybrid vehicle, because a first battery or electric power generator is connected to a motor controller and engine controller, even if a high voltage line including an electric motor has broken down, such a hybrid vehicle can run using the engine only.
Moreover, in a control apparatus for a hybrid vehicle, the first battery or electric power generator is connected to an engine controller. A second battery and electric motor are connected to a motor controller through a DC/DC converter. Accordingly, the engine controller side that is a low voltage system including the engine and the motor controller side that is a high voltage system including the electric motor are completely independent. Even if it is assumed that the motor controller side that is a high voltage system has failed, this system receives no influence, and such a vehicle can be driven by only the engine controller side which is a low voltage system.